Grass mowing machines known as ZTR mowers have at least one independently powered drive wheel on each side of a frame. One drive wheel may be operated in a forward direction while the other drive wheel may be stopped or operated in reverse. Many ZTR mowers have a twin stick control system. A pair of control levers or sticks may be provided side-by-side, with each lever or stick controlling one of the drive wheels. When both levers or sticks are advanced together forwardly out of their neutral position, both drive wheels rotate forwardly to cause the mower to move forward. A ZTR mower may be steered by advancing one lever or stick more than the other.
Typically, each control lever or stick on a ZTR mower may be linked to a pump arm of one of two separate hydraulic pumps, or of a dual hydraulic pump; i.e, a separate pump for each wheel. The lever or stick may be used to move a pump swashplate through a direct linkage.
The control levers or sticks on a ZTR mower may be mounted on the vehicle frame so that each has a first pivot axis allowing the lever or stick in the operating position to pivot forwardly in an arc to turn the wheel in forward, or pivot rearwardly to turn the wheel in reverse. Additionally, each lever or stick may pivot outwardly in an arc from the operating position to a non-operating or parked position. Some levers or sticks may pivot outwardly to activate a safety switch which can deactivate the PTO and/or cutting blades, to enhance safety of an operator who is exiting or entering the operator seat or platform.
In the past, the left and right hand control levers or sticks were mounted on a ZTR mower with separate left and right control mechanisms to allow pivoting of the levers. The pivot mechanisms typically were made from sheet steel, rod and tubing, and included a bracket to mount a plunger-type safety switch near the part on the lever that activates the plunger on the switch. Additionally, the control levers or sticks could not be readily sized or mounted to optimize operator comfort. For example, ZTR mowers did not allow adjustment of the height of the control levers and the position of the levers relative to the operator seat or platform.
There is a need for a light weight, inexpensive, dual lever steering control mechanism for mounting control levers or sticks on ZTR mowers. There is a need for a dual lever steering control mechanism that can be used interchangeably to mount either the left or right control levers or sticks to a ZTR mower. There is a need for a dual lever steering control mechanism having a minimum number of parts and components to simplify manufacturing and assembly. There is a need for a dual lever steering control mechanism that can allow the levers to be safely and securely adjusted up/down and fore/aft for optimal operator comfort.